alt Hacker NewsNah, Android is not a really a proper Linux system that 'supports' Linux software within any reasonable definition of the word; not anymore at least
Root nowadays gets you very little: software like wavemon that worked great on Android 4.4 no longer runs because selinux or whatever restrictions block nearly everything from working that isn't going through the Android API channels. Accessing external storage from Linux Deploy (running your favorite distro in userspace with root) no longer works; thankfully it does from Termux so I have some way of manipulating the files with standard Linux tools, but then that keeps getting killed and you need to restart sshd a few times per day if you want to actually use that as a remote access method for your photos.
The Linux processes are being shot at left and right, it's go android or go bust on android. Perhaps that sounded redundant but it used to be that you could install Xorg, Virtualbox and other GUI software, and knock yourself out. No more
Most of this is not related to the claim and is more tangential discussion about things you like that run on the linux kernel, now, there is nothing wrong with that, but I must emphasise that none of what you describe is a part of the criteria for what constitutes a linux distro. A linux distro is an operating system using the linux kernel. Android fits that criteria.
The policies and applications running on top of or in the linux kernel do not change its distro classification. Lacking root access is a massive step forward for privacy and security. Root access is insecure and a hacky shortcut to proper functionality.